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A057749 Prime degrees of absolutely reducible trinomials: primes p such that x^p + x^k + 1 is reducible over GF(2) for all k, p>k>0. 1
13, 19, 37, 43, 53, 59, 61, 67, 83, 101, 107, 109, 131, 139, 149, 157, 163, 173, 179, 181, 197, 211, 227, 229, 251, 269, 277, 283, 293, 307, 311, 317, 331, 347, 349, 373, 379, 389, 397, 419, 421, 443, 461, 467, 491, 499, 509, 523, 541, 547, 557, 563, 571 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..53.

MATHEMATICA

Do[ k = 1; While[ ToString[ Factor[ x^Prime[ n ] + x^k + 1, Modulus -> 2 ] ] != ToString[ x^Prime[ n ] + x^k + 1 ] && k < Prime[ n ], k++ ]; If[ k == Prime[ n ], Print[ Prime[ n ] ] ], {n, 1, 144} ]

PROG

(PARI) lista(nn) = {forprime(p=2, nn, ok = 1; for (k=1, p-1, if (polisirreducible(Mod(1, 2)*(x^p + x^k + 1)), ok = 0; break); ); if (ok, print1(p, ", ")); ); }

CROSSREFS

Sequence in context: A275660 A088186 A089490 * A040070 A322923 A048523

Adjacent sequences:  A057746 A057747 A057748 * A057750 A057751 A057752

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Oct 30 2000

STATUS

approved

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Last modified October 19 16:17 EDT 2019. Contains 328223 sequences. (Running on oeis4.)